Patent GB-993063-A (GB)
Title: Photoelectric sorting machine
Inventor: FRAENKEL HERBERT
IPC: G01N21/64
Filed: 1962-04-30
Abstract: 993,063. Controlling sorting photo-electrically. GUNSON'S SORTEX Ltd. April 22, 1963 [April 30, 1962], No. 16493/62. Heading G1A. A sorting machine has at least two photoelectric viewing means which respectively respond to and/or are arranged to receive light of different wavelengths from each object to be sorted at least one of the said means being responsive to and arranged to receive light produced by fluorescence from each object. One embodiment (Fig. 1 not shown) utilises a Y-shaped light guide to direct light due to fluorescence of each object sorted, to two separate photo-cells or photomultipliers each photo-cell receiving light of a different colour due to interposed filters. The signals from the photocells are fed to a difference amplifier whose output is connected as before to an electronic comparator controlling an ejector blower. Filters are mounted in front of the illuminating lamps to prevent light of the same colours as that of fluorescence from reaching the objects. In the arrangement shown an object such as a ground nut 2 falling from a conveyer 49 is illuminated by infra-red and ultra violet radiation from sources 44 and 43 respectively through infra-red and ultra violet filters 48 and 47 respectively, and radiation consisting of light due to fluorescence of the nut and reflected infra-red radiation from the nut 2 and a reflecting background 50 is directed by a lens 51 through a hole 54 in the flange 52 of a rotating scanning disc 52, on to the end of a light guide 55. Radiation emerging from the other end of the light guide 55 is split into two beams by a beam splitter 27, one beam passing through a filter 30 which passes infra-red radiation only to a photo-cell 31 and the other beam passing through a filter 32 which passes only light of the colour in which undesirable toxic moulds if present on the nut will fluoresce to a photo-cell 33. The signals from the photo-cells are compared with each other and against standards in an amplifier 34 which controls an ejector device 35. The purpose of using infra-red radiation with the background 50 as well as ultra violet is to compensate for the effect of unskinned nuts on the operation of the equipment. The quality of sorting may be improved if a further light splitter 36 is provided which directs part of one beam from the splitter 27 on to a further photo-cell 38 through a filter 37 which transmits light due to fluorescence of the nut 2 but of one colour only, this being different from the colour transmitted by the filter 32. The output from the photo-cells 33 and 38 are compared at a difference amplifier 40 the resultant signal being fed to the amplifier 34. The arrangement of Fig. 3 is provided with further lamps 43, 44 lenses 51 and light guides 55 (not shown) the various lenses viewing nuts travelling along different paths, and directing the radiation on to different portions of the flange 52 the various light guides extending to said portions, so that as the disc 52 rotates the photo-cells receive the radiation in successive paths. In a simplified arrangement (Fig. 2 not shown) only a single path is used and therefore the light guide and scanning disc 52 are not used. In another embodiment (Fig. 4 not shown) the background 50 is not used, instead the nuts drop between the infra-red source and the lens 51. The lamps 43, 44 may be replaced by a single lamp producing both infra-red and ultra violet radiation Alternatively a single lamp producing ultra violet radiation may be used in which case the photo-cell 31 is arranged to be sensitive to ultra violet only and the filter 30 transmits ultra violet radiation only.